The overall objectives of the project are to: (1) Confirm the existence of myosin-linked regulation in vascular smooth muscle; (2) Isolate phosphorylation-dependent, calcium-regulated myosin from smooth muscle; (3) Investigate the role of phosphorylation in the regulatory mechanism; (4) Measure the physical properties and study the interactions of the smooth muscle myosin subunits in the regulatory mechanism; and (5) Determine whether or not head-to-head interactions are important in the regulatory mechanism.